Block Copolymer Pattern Formation for Wire Grid Polarizing Plates
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Solution Overview
Problem
The existing methods for manufacturing wire grid type polarizing plates face challenges such as step differences in wire height leading to deteriorated optical characteristics and poor heat resistance due to the use of PET sheets, and the complexity of etching glass substrates to form mask patterns.
Innovation Solution
A pattern formation method using a block copolymer that forms a lamellar structure through microphase separation, involving the creation of guide and neutral patterns on a base material, followed by heat treatment and selective removal of block chains to form a line-and-space-shaped fine pattern, which is then used to etch a metal film on a transparent substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photoresist pattern formed by the photolithography method is set as the mask pattern, then the mask pattern can be formed, but a major alteration on a process such as shortening of a wavelength of a light source and employing of an immersion exposure method is necessary to narrow the pitch of the mask pattern
Solution Approach 1:
The invention changes the fundamental parameter of pattern formation from photolithography to block copolymer self-assembly. Instead of altering photolithography parameters (wavelength, immersion), it uses the natural microphase separation of block copolymers to achieve the desired pitch, thereby avoiding complex process alterations while achieving sub-100nm pitch precision
Solution Approach 2:
The invention replaces the mechanical/chemical photolithography system with a self-organizing block copolymer system. The block copolymer chains spontaneously organize into lamellar structures through microphase separation, eliminating the need for complex photolithography equipment and process modifications
2Manufacturing precision
If a pattern formed by the nanoimprint method is set as the mask pattern, then the mask pattern can be formed, but in order to narrow the pitch of the mask pattern, it is necessary to manufacture a mold conforming to the pitch, and thus it is difficult to narrow the pitch
Solution Approach 1:
The block copolymer system performs self-service by automatically organizing into the desired pattern through microphase separation. The system self-assembles the mask pattern without requiring external mold fabrication, thereby achieving narrow pitch without the difficulty of manufacturing precision molds
Solution Approach 2:
The invention changes the pitch control mechanism from mold-based physical constraints to block copolymer chain length and composition parameters. By adjusting the block copolymer structure rather than manufacturing molds, pitch narrowing becomes feasible without complex mold manufacturing
3Ease of manufacture
If the metal film is formed on the entirety of the base body surface including the bottoms of the grooves, then the mask pattern can be formed, but a step difference occurs in the height of the wires in correspondence with the depth of the grooves, and this leads to deterioration of optical characteristics
Solution Approach 1:
The invention extracts the problematic groove structure from the base body surface. Instead of forming grooves and filling them with metal film (which creates step differences), the block copolymer method forms a flat mask pattern directly, eliminating the source of wire height non-uniformity
Solution Approach 2:
The invention inverts the conventional approach: instead of forming grooves first and then creating the mask pattern within them, the block copolymer method forms the mask pattern on a flat surface, thereby inverting the sequence and eliminating step differences that would otherwise require additional processing to correct
4Ease of manufacture
If the base body such as the PET sheet is used, then the mask pattern can be formed, but the polarizing plate obtained has poor heat resistance
Solution Approach 1:
The invention extracts the PET base body from the manufacturing process. By eliminating the PET sheet entirely and using only a transparent substrate with metal film, the heat resistance problem is solved while mask pattern formation is achieved through the block copolymer method
Solution Approach 2:
The block copolymer acts as a temporary copying medium for pattern formation. The pattern is formed by the block copolymer's self-assembly, then transferred to the metal film for etching, allowing the removal of the block copolymer and eliminating the need for heat-sensitive PET base bodies
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of polarizing plates with improved optical characteristics and heat resistance by forming a wire grid structure with a smaller pitch, suitable for advanced optical applications.
Implementation Method 1
a lamellar structure is formed by microphase separation of the block copolymer
Data Source
AI summary
Provided are a pattern formation method and a method for manufacturing a polarizing plate using the pattern formation method, the pattern formation method having: a step for forming, on a substrate, a linear guide pattern which is arranged at a predetermined pitch and is compatible with a portion of block chains of a block copolymer, and a neutral pattern embedded in the pattern of the guide pattern; a step for forming a layer including a block copolymer on the guide pattern and the neutral pattern; a step for heat-treating the layer including the block copolymer and forming a lamellar structure in which lamellar boundaries are arranged perpendicular to the substrate by microphase separation of the block copolymer; and a step for selectively removing a portion of the block chains of the block copolymer and thereby forming a line-and-space-shaped fine pattern having a smaller pitch than the guide pattern.